The action comes after the Hillsborough County Aviation Authority, which controls Peter O. Knight Airport on Davis Islands, asked the city to clear the 35 boats blocking the airport's seaplane corridor.

The remaining boats have been asked to move until the city can create a formal, legal mooring field similar to one on the waterfront at St. Petersburg.

“We can't even begin the process until the basin is cleared,” McElroy said.

The boats are registered to owners scattered from Venice to Painted Post, N.Y. The bulk of the owners are from Tampa. A few have Davis Islands addresses. Police couldn't find owners for eight of the boats.

Glen Grogg was among those who got a notice. He came home Monday to find the orange sign stuck to his 32-foot sailboat.

Grogg has lived in the seaplane basin for 23 years. He remembers the last time the city issued warnings to boat owners a decade ago.

“We all pitched in and got a lawyer,” said Grogg.

Grogg — “Red” to his friends — was severely injured in a hit-and-run car wreck several years ago. He said living on his boat helps him stretch his budget of $600 a month. The seaplane basin puts him close to Tampa General Hospital, where he is undergoing treatment for cancer.

He's not happy with the eviction notice.

“Where will I go?” he said Wednesday as he sat on the front porch of a houseboat belonging to his friend Arnie Wysocki.

Any legal mooring or marina would cost Grogg hundreds of dollars, Wysocki said.

“A guy like Red can't afford to put his boat in a slip, can't afford a car. But he's got a right to live,” Wysocki said.

Wysocki brought his houseboat up from Apollo Beach for a brief visit. He has lived on boats for 30 years. He said the situation in the seaplane basin, which used to host a few dozen boats, has gotten out of hand.

“Something needs to be done with it,” he said. “There's way too many boats out there.”

Some of the boats are derelict. One is taking on water; another has sunk and been salvaged several times. Most of them sat empty and quiet on Wednesday afternoon, floating near the buoys that marked their submerged moorings.

State law says cities and counties cannot block boaters from anchoring where they will. But McElroy said that's not what's happening at Davis Islands.

Instead, most of the boats are attached to some heavy object sitting on the bottom of the basin, such as a concrete block.

“The boats are illegally moored,” McElroy said. “They're not just pulled up and dropping anchor.”

The warnings issued by police give the boat owners 30 days to find new homes for their vessels. McElroy said the city will work with owners who need a little more time, but the goal is to have the basin cleared early next year so work can begin on the mooring field.

It could be years before the city finishes a formal mooring field, which is likely to have significantly fewer tie-ups than the seaplane basin has now.

St. Petersburg's 13-spot mooring field took six years from inspiration to realization. It opened in 2012. The largest chunk of the development time was spent securing permits from state and federal agencies, said Walt Miller, manager of the city's marina and port.

St. Petersburg created a formal mooring field in downtown's North Yacht Basin to put an end to the informal system in which people often abandon their boats, Miller said. The mooring field charges by the night and has a maximum stay of three months.

Under Tampa's plan, boat owners who don't leave the seaplane basin voluntarily will find their vessels towed away and stored. But that's a last resort, McElroy said.

“We're working with boat owners because the last thing we want to do is impound boats,” she said.